The Green Grid offers new measures of datacenter efficiency

Building on its earlier measures which focused on the efficiency of datacenter …

The Green Grid is a member-run organization that focuses on improving the efficiency of what's become a major energy sink: corporate datacenters. The group, which includes both vendors and users of datacenter hardware, has had great success with an earlier measure of datacenter efficiency, called Power Usage Effectiveness, that helped determine which fraction of a facility's power budget went to running the actual hardware. Now, it's working on providing some measures of how efficiently that hardware is working.

The Green Grid's Mark Monroe (who has a day job with Sun Microsystems) talked to us about the new efficiency measures and other news that's being announced at the group's annual meeting. Monroe said the Grid is building on what it considers the success of the earlier Power Usage Effectiveness measure, which is simply the total power used by a facility divided by the power that runs the actual computing hardware. Despite its simplicity, the measure effectively captures the efficiency of things like the climate control equipment that keeps the compute hardware humming along safely. "The impact of having a metric," Monroe said, "is that, over time, people are starting to focus on it." You can see that in some of the healthy competition between Google and Microsoft over their datacenters' PUE numbers.

The next obvious step, Monroe said, is to have a good metric that tracks how much useful work the hardware is performing with the power budget. It's already provided a measure, called DCeP, that attempts to do so, but the procedure for obtaining a DCeP value was far more complex than the easy-to-use PUE metric, so the Grid is now focused on providing its users with a set of proxy measurements that, while not as accurate as a DCeP, are far easier to obtain, and thus potentially more useful. A document describing a set of eight proposed proxies has been posted on the Green Grid Web site.

The proposed proxies cover a lot of ground, in part because useful work can be a very slippery thing to define. Outbound data might be a reasonable measure of a Web server's efficiency, but it makes no sense for something that's hosting a backup archive or a compute cluster. As such, the Green Grid expects it will accept several of the proposed proxies after receiving feedback on their use. So, for example, one of the proposed proxies simply divides the total bits flowing through outbound routers by the total power use, while another uses SPECint_rate as the basis for the calculation.

But two of the more intriguing measures show how widely the concern with datacenter power use has spread through the industry. One relies on the recently developedSPECpower measurement, which allows manufacturers to rate the power efficiency of specific hardware configurations; the DCeP proxy would simply involve summing the figures for the datacenter's hardware list.

Intel has also provided the Green Grid with an SDK called Productivity Link, which developers can incorporate into their applications (Intel has made power consumption a focus). After implementing five functions with an estimated ten lines of code, their applications can report in on how they're performing. The SDK contains scripts for drawing reports standard server apps that will run on Solaris, OS X, Linux, and Windows; if the API isn't implemented, the scripts will default to checking various processor-level performance registers.

Obviously, the results can't really be compared between proxies, but they could definitely help a facility track its performance over time as the mix of equipment changes, and test how things like virtualization and different air conditioning practices influence the datacenter's performance.

The new efficiency measures are just one of the efforts directed to giving companies a better sense of how to improve datacenter power use. Monroe also highlighted a recent whitepaper that the group produced on the use of virtualization as a driver of efficiency, and highlighted a number of new initiatives that are being announced at the annual meeting.

Several of these involve collaborations between the Green Grid and the US government. The grid is now hosting a site developed by the Department of Energy as part of an expanding partnership. One of the DOE's labs will help in evaluating the different DCeP proxies, and the Department is developing maps of the potential for free cooling of datacenters—plug in a zip code to an online Web app and the desired temperature and humidity, and the site will tell you how many days a year you can skip running the air conditioning while staying within the parameters, along with how much money that will save. The group is also working with the EPA to help finalize the first Energy Star standards for datacenter equipment.

It no longer seems necessary to expend much effort to convince anyone involved in enterprise IT that getting an energy efficient data center is an economic necessity, but it may still be necessary to help managers decide what the best place to start is, and provide ways of measuring progress. The steadily expanding arsenal of tools should help integrate energy efficiency measures into every stage of IT planning.